# Applying pressure to bottom half of a cylindrical surface with existing hex mesh

**URL:** <https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202>\
**Category:** General Questions\
**Created:** [May 26, 2022, 6:52am UTC](https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202 "2022-05-26T06:52:44Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![suleymanmuti](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@suleymanmuti](https://prepomax.discourse.group/u/suleymanmuti)\
**Post date:** [May 26, 2022, 6:52am UTC](https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202/1 "2022-05-26T06:52:44Z")

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Hello. I am trying to repeat [this example](https://classes.engineering.wustl.edu/2009/spring/mase5513/abaqus/docs/v6.5/books/gsa/default.htm?startat=ch04s03.html) with PrePoMax. I have all hex mesh of the part from an existing .unv file. I want to apply pressure on the bottom half of the cylindrical inner face. I have a node set containing all of the nodes belonging to this surface. However, in PrePoMax when applying pressure I cannot select the node set. I can apply pressure to using PrePoMax to a surface but I can select the whole cylindrical surface, not the bottom half. I appreciate your suggestions.

 ![Untitled](https://global.discourse-cdn.com/free1/uploads/prepomax/original/1X/8bb7a6a65fef0eee7b40ede52419cbb96e78d0e5.jpeg)

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [May 26, 2022, 8:01am UTC](https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202/2 "2022-05-26T08:01:14Z")

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In both PrePoMax and Abaqus pressure must be applied to element faces. If you can’t define a surface in the mesher of your choice and then export the .inp file including this surface definition then you have to create a surface in PrePoMax manually. Box selection (and deselection) with these settings should help:

 ![mesh selection](https://global.discourse-cdn.com/free1/uploads/prepomax/original/1X/275a059aae7b1099b92fef11a66b19a9cb714b0e.png)

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<div class="post-metadata">

**Author:** ![suleymanmuti](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@suleymanmuti](https://prepomax.discourse.group/u/suleymanmuti)\
**Post date:** [May 26, 2022, 8:45am UTC](https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202/3 "2022-05-26T08:45:21Z")

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Hello Jakub. I created a surface using the create surface with surface type node. When applying the pressure, however, I cannot point to the surface just created since ‘Region type’ only has ‘Selection’ property unlike surface creation where there is also another property, ‘NodeSet’.

 ![Untitled](https://global.discourse-cdn.com/free1/uploads/prepomax/original/1X/289fe4c5b86984f052c537edfddf60f5e81123df.png)

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [May 26, 2022, 9:01am UTC](https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202/4 "2022-05-26T09:01:33Z")

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What I meant is that you should select _Node_ in _FE mesh based selection_ window. Leave the _Surface type_ as _Element_. Like in the screenshot I attached before. Then the surface will be selectable when defining pressure.

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<div class="post-metadata">

**Author:** ![suleymanmuti](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@suleymanmuti](https://prepomax.discourse.group/u/suleymanmuti)\
**Post date:** [May 26, 2022, 10:37am UTC](https://prepomax.discourse.group/t/applying-pressure-to-bottom-half-of-a-cylindrical-surface-with-existing-hex-mesh/202/5 "2022-05-26T10:37:08Z")

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Thank Jakub. Works perfectly. 👏